Oil is a natural substance found miles below the earth’s surface. It is the result of millions of years of decaying trees and dead matter undergoing large amounts of pressure as it becomes buried deep beneath the earth’s surface.
When in large quantities oil can be a very damaging chemical for marine life due to its sticky, slimy and, well, oily nature. Oil can enter the sea in many ways, either from inland through rivers and outlets, from ships and tankers when they run aground, or from oil drilling. It can also make its own way onto the surface of the earth, these natural areas are known as oil seeps.
Although oil enters the sea from many sources and can even occur naturally in marine environments it is the often massive scale of human oil spills that cause devastating effects to wildlife and ecosystems. Don’t be fooled by the word ‘spill’ either - the largest ever oil spill is said to have been the Deepwater Horizon oil spill in the Gulf of Mexico in April 2010 where about 4 million barrels of oil were spilt affecting 4000 miles of coastline.
The location of an oil spill also affects how damaging the slick is - areas rich in wildlife, or habitats that are particularly fragile such as coral reefs, can expect to suffer more. A spill near a sandy beach makes clean up operations much harder than spills on rocky cliffs. Birds are especially prone to problems if the oil gets onto their feathers which are naturally water repellent. Birds that become covered in the thick and sticky substance are no longer waterproof which makes swimming or flying impossible. And if swallowed the toxic oil can damage organs and cause death.
Oil can take months or even years to disappear and is a tricky substance to clean up. It does break up naturally but when there are several thousand tonnes of it we need to step in and help clear it up. Ways of dealing with spills and slicks are by soaking it up, adding chemicals to it to break it up and make it less harmful, sucking it up with a big machine a bit like a vacuum hoover, skimming it off of the sea’s surface or burning and evaporating it.
Crude oil is made up of over 1,000 chemicals. Of these, the light hydrocarbons, which are used to make petrol and aviation fuel are the most toxic. In warm conditions, these usually evaporate quite quickly, making a foul smell, but reducing the danger to wildlife. In cold seas, however, the process of evaporation can be very slow, and this means the risk to wildlife lasts longer. To prevent this, the light hydrocarbons are often burned off the surface of the sea.
In the UK, there are a group of patrol aircraft whose job it is to search for oil floating on the surface of the seas. The spotter planes are able to distinguish different types of oil, and work alongside dispersant-spraying aircraft so that oil can be treated quickly and in the most effective way possible.
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